How to merge multiple empties into 1 average empty
You can set the cursor to the midpoint of those Empties and create a new Empty at the cursor location:



Select your empties
Set the Transform Pivot Point to Median Point
Place the cursor at this middle point: Right Click to show the Object Context Menu > Snap > Cursor To Selected (or press Shift + S > Cursor To Selected)
Create the Empty: Shift + A > Empty